1. Field of the Invention
The present invention relates to foamed materials and to the manufacture thereof. In particular, the invention relates to the use of filaments of foamable polymeric material in the manufacture of a foamed fabric. The invention further relates to novel uses of such a foamed fabric which exhibits good impact resistance and cushioning while maintaining an open structure, allowing good ventilation or drainage.
2. Description of the Related Art
Foamed material is used in various applications for the purpose of cushioning or shock absorption. It has been available in sheets, mats and blocks since the 1930s as foam rubber. Initially natural latex rubber and styrene-butadiene rubber materials were used. More recently, polyurethane foams based on isocyanate have become common. Synthetic foam can be manufactured in various grades of density, thickness and softness according to the required use. It can also be present as open-cell foam or closed-cell foam, depending on the nature of the material and the method of manufacture. Closed-cell foam generally has the advantage that it can be exposed to moisture without the moisture being absorbed by the cell structure. Another advantage is that cushioning is much greater, since the closed cells can better absorb the force. A disadvantage of closed-cell foam is that it cannot transmit air or moisture. For many applications where moisture or air transport is required, existing foamed materials are unsuitable. Attempts have been made to improve the transport properties of foam materials e.g. for use in mattresses, by perforating a foam sheet with holes. An example of an aperture mattress insert is shown in U.S. Pat. No. 4,536,906. Such products do provide additional advantages but are still limited in their function. A foam insole for a shoe is shown in US2009119953, whereby apertures are provided to increase ventilation. Underlay shock pads of closed cell foam are also known in which apertures are formed to ensure adequate drainage, in particular, the ProGame™ shock pad from Trocellen GmbH.
It is also desirable to use foam materials in other situations where impact absorption or cushioning can be required. This can be required as a layer in protective garments, furnishings and the like. In such contexts, breathability is also often a requirement. So too is the ability to integrate the foam layer within a multi-layer structure, often around a complex shape. It would be desirable to provide an alternative construction for a fabric that allowed the use of closed-cell foam material while maintaining desirable properties of breathability and water transport. Additionally, existing foam layers have a fixed two-dimensional form i.e. they can flex but cannot easily skew in the plane of the layer without deformation. In the past, underlays and mats formed of foam material have been subject to creasing and distortion due to their inability to skew or stretch
Additionally, foamed layers are generally of relatively low strength, especially when present as relatively thin layers. Attempts to improve on the strength of foam have considered the incorporation of fibrous materials. An example of a foamed laminar product with incorporated reinforcement fibres is given in EP2177335. Attempts have also been made in the past to integrate foam material into textile like constructions. DE 2730915 shows the use of open-cell foam strips woven together to form a carpet underlay. The handling of strips of foam material is difficult and integration of such foam strips into a fabric is not easily achieved. It would be desirable to provide an improved process by which foamed fabric layers could more easily and conveniently be produced.